Some computing systems provide electronic messaging (e.g., e-mail) services that facilitate electronic communication between users of computing devices. During an e-mail exchange, participating users communicate back and forth with each other, sometimes responding to inquiries made by others in subsequent e-mail replies. Some e-mail systems may analyze draft replies prior to the sending of the draft reply. For example, a system analyzes a draft email for indications of potentially missing attachments. If the body of the draft email, for example, makes reference to an attachment, but the user has not yet attached any file to the draft email, the system may prompt the user with a warning indicating that the user may have forgotten to add an attachment.